JPH0738812A - Image pickup device equipped with image pickup element for multichannel output - Google Patents

Abstract

PURPOSE:To improve adjustment precision by extracting respective channel outputs from an image pickup means comparing the extracted data, operating a DC voltage level adjustment quantity and a gain adjustment quantity, and automatically adjusting a DC voltage level and a gain. CONSTITUTION:A CPU 10 reads an offset error and a gain error out of an EEPROM 14 and sends them out to a D/A unit 11. The unit 11 converts the error values into control voltages and sends them out to offset adjusting circuits 4a and 4c and amplifying circuits 5a and 5c. A CCD 1 picks up a subject image, accumulates electric charges corresponding to the luminance, pixel by pixel, and outputs the accumulated pixel information in synchronism with the clock from a CCD driving circuit 2. The outputted information is outputted to the circuits 4a-4c through noise reduction and sample and hold circuits 3a-3c and the reference DC voltages levels of the respective channels are adjusted and equalized. Further, the gains of amplifying circuits 5a-5c are adjusted so that the signal amplitudes of the respective channels become equal. Consequently, the adjustment precision is improved and the adjustment is automated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus using an image pickup device having a plurality of channel outputs, and more particularly to an improvement in offset adjustment and gain adjustment between channels.

[0002]

2. Description of the Related Art An image pickup device has been conventionally used for photographing with a camera, but in order to increase the resolution of a photographed image, it is necessary to increase the number of pixels of the image pickup device used for photographing. However, when the number of pixels of the image sensor is increased, there is a drawback that it takes time to output all pixel information.
On the other hand, if the time for outputting each piece of pixel information is shortened in order to shorten this time, noise is likely to occur and there is a possibility that pixel information cannot be faithfully recorded and reproduced. Therefore, an image pickup device using an image pickup device provided with a plurality of output terminals (hereinafter referred to as a multi-channel output image pickup device) and simultaneously converting pixel information into a single video signal by using a multiplex circuit or the like Has been used for a long time. In such an image pickup device, since pixel information of a plurality of channels is simultaneously output from the image pickup element, it is not necessary to increase the output speed of each pixel information, and it is less susceptible to noise and has an advantage of excellent transfer efficiency. Have.

[0003]

In the image pickup apparatus using this multi-channel output image pickup device, offset adjustment (DC voltage level of pixel information) is separately performed for each channel for pixel information output from the image pickup device. Adjustment) and gain adjustment (adjustment of the amplitude value of the pixel information), there is a possibility that the DC voltage level and the amplitude value may vary among the channels. Therefore, in an image pickup apparatus using such an image pickup element, the above variation is adjusted at the time of assembly, shipping, or the like. However, even if the variation is adjusted at the time of shipment of the image pickup device, the DC voltage level and the amplitude value may vary from channel to channel due to changes in temperature, changes over time, and so on. Is generally not easy because it is difficult to determine the reference value and fine adjustment is required.

An object of the present invention is to calculate the adjustment amount of the DC voltage level and the adjustment amount of the gain by comparing the output values of the respective channels when an image is picked up by an image pickup means having a plurality of channel outputs. An object of the present invention is to provide an image pickup device capable of automatically adjusting the DC voltage level and the gain.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1 showing an embodiment. In the present invention, the image pickup means 1 having a plurality of channel outputs, and the DC voltage of each channel output from the image pickup means 1 are described. DC voltage adjusting means 4 for adjusting the level
The extraction means 8 is applied to an image pickup apparatus having a, 4b, 4c and amplification means 5a, 5b, 5c for applying a gain to each channel output from the image pickup means 1, and extracts each channel output from the image pickup means 1, respectively. And by comparing the extracted data for each channel extracted by the extracting means 8,
The DC voltage level adjusting amount and the gain adjusting amount are calculated, and the DC voltage adjusting units 4a, 4b, 4 are provided.
By configuring c to adjust the DC voltage level based on the result of the calculating means 10 and adjusting the gains 5a, 5b and 5c to adjust the gain based on the result of the calculating means 10, the above object is achieved. To be achieved. According to a second aspect of the present invention, in the image pickup apparatus according to the first aspect, the calculating means 10 obtains a difference between the extracted data of a predetermined channel and the extracted data of another channel, and the DC voltage is calculated according to the difference. The configuration is such that the level adjustment amount and the gain adjustment amount are calculated. The invention described in claim 3 is the invention according to claim 2.
In the image pickup apparatus described in 1), the first evaluation means 10 for determining whether or not the extracted data extracted by the extraction means 8 is suitable for obtaining the difference by the calculation means 10, and the first evaluation means 10. The difference obtained by determining that
A second evaluation means 10 for determining whether or not it is suitable for calculating the DC voltage level adjustment amount and the gain adjustment amount, and the calculation means 10 is determined to be suitable for the second evaluation means 10. Then, the DC voltage level adjustment amount and the gain adjustment amount are calculated.

[0006]

In the invention described in claim 1, the calculating means 10 compares the extracted data for each channel extracted by the extracting means 8 to calculate the DC voltage level adjustment amount and the gain adjustment amount, and the calculated result is obtained. DC voltage adjusting means 4a based on
4b and 4c adjust the DC voltage level, and amplifying means 5a and
5b and 5c adjust the gain. According to the second aspect of the present invention, the calculation means 10 calculates the DC voltage level adjustment amount and the gain adjustment amount according to the difference between the extraction data of a predetermined channel and the extraction data of another channel. In the invention according to claim 3, the first evaluation means 10 determines whether or not the extracted data extracted by the extraction means 8 is suitable for obtaining the difference by the calculation means 10, and the first evaluation means 10 is determined. If it is determined that the difference is suitable, the second evaluation means 10 determines whether the difference is suitable for calculating the DC voltage level adjustment amount and the gain adjustment amount, and the second evaluation means 10 When the means 10 determines that it is suitable, each adjustment amount is calculated.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a block diagram of an embodiment of an image pickup apparatus according to the present invention. In this embodiment, a CCD (Charge Coupled Device) having three-channel output is used as an image sensor.
se) will be described. 1 is a CCD having three-channel output,
It outputs from three output terminals b and c (hereinafter referred to as a channel, b channel, and c channel). In this embodiment, the DC signal level and the gain of the a and c channels are adjusted using the output signal of the b channel as a reference signal. Reference numeral 2 denotes a CCD drive circuit, which supplies the CCD 1 with a clock for instructing the transfer of imaged pixel information, and also supplies various clocks synchronized with the pixel information transfer speed to each unit of the image pickup apparatus. Reference numerals 3a, 3b and 3c denote noise reduction & sample hold circuits, which remove noise from pixel information of each of the a, b and c channels output from the CCD 1 and then perform a known method such as correlated double sampling on each channel. Sampling every. Four
Offset adjustment circuits a, 4b, and 4c adjust the DC voltage for each channel, and adjust so that the reference DC voltage levels of the pixel information of each channel are all equal.
The reference voltage level of the offset adjustment circuit 4b is adjusted by a preset control voltage, and the reference voltage level of the offset adjustment circuits 4a, 4c is adjusted by control voltages Oa, Oc input from a D / A unit 11 described later. To be done.

Reference numerals 5a, 5b and 5c are amplifiers for amplifying the output of the CCD 1, amplifier 5b is a fixed amplifier for amplifying with a preset gain, and amplifiers 5a and 5c are
Control voltages Va and Vc from a D / A unit 11 described later
It is a voltage-controlled amplifier whose amplification degree changes depending on the size of. Thereby, the maximum and minimum signal amplitudes of the respective channels are adjusted to be equal. Reference numeral 6 denotes a multiplex circuit, which sequentially switches the outputs of the amplifiers 5a, 5b, 5c to convert them into one video signal and outputs it. 7 is A / D
The A / D converter 7 is a converter to which a clock synchronized with the transfer rate of pixel information is input from the CCD drive circuit 2, and the video signal is converted into a digital signal in synchronization with this clock. A sampling circuit 8 samples a part of the pixel information converted into a digital signal by the A / D converter 7. The sampled pixel information (hereinafter referred to as sampling data) is stored in the buffer memory 9, and this sampling data is used to calculate gain error and offset error between channels.

Reference numeral 10 denotes a CPU, which uses the sampling data stored in the buffer memory 9 to calculate a gain error and an offset error. Reference numeral 11 is a D / A unit, which uses the gain error and the offset error calculated by the CPU 10 so that the control voltages Oa, Oc, Va and Vc are set to the offset adjusting circuits 4a and 4c so that the respective errors become zero. It is sent to the amplifiers 5a and 5c. Reference numeral 12 is a signal processing circuit, which performs processing such as γ correction, contour correction, and black and white clipping on the video signal output from the multiplex circuit 6. A D / A converter 13 converts the output of the signal processing circuit 12 into an analog video signal.
This analog video signal is input to a monitor or the like, and a captured image is reproduced and recorded. 14 is an electrically erasable programmable ROM (hereinafter referred to as EEPROM),
The offset error and gain error for each channel are stored in advance, and when the power is turned on, the control voltages Oa, Oc, Va, Vc corresponding to these values are supplied to the offset adjustment circuits 4a, 4c and the amplifiers 5a, 5c. Each is set.

The operation of the first embodiment will be described below with reference to FIG. When a power source (not shown) of the image pickup apparatus is turned on, the CPU 10 reads out the offset error and the gain error stored in the EEPROM 14 and sends them to the D / A unit 11. The D / A unit 11 converts these error values into control voltages Oa, Oc, Va, Vc and sends them to the offset adjustment circuits 4a, 4c and the amplification circuits 5a, 5c. When the CCD 1 captures a subject image, the CCD drive circuit 2 accumulates charges corresponding to the brightness of each pixel.
The accumulated pixel information is output in synchronization with the clock from. The output pixel information is passed through the noise reduction & sample hold circuits 3a, 3b, 3c,
It is input to the offset adjustment circuits 4a, 4b, 4c and adjusted for each channel so that the reference DC voltage levels of each channel are all equal, and then the amplification circuits 5a, 5b,
In 5c, the gain is adjusted for each channel so that the signal amplitude of each channel becomes equal. The offset adjusting method and the gain adjusting method will be described later.

The channel signals whose gains have been adjusted by the amplifier circuits 5a, 5b and 5c are converted into one video signal by the multiplex circuit 6 and then converted into digital signals by the A / D converter 7, Processing circuit 12 and sampling circuit 8
Sent to. The sampling circuit 8 samples a part of the pixel information converted into a digital signal. However, if the number of samples is too small, for example,
If noise happens to be present in the pixel information at the sampled location, the error in the overall sampling result increases, so the number of samplings is large enough to absorb the effects of noise, for example, 10 for each channel.
About 24 samples are sampled. When sampling is performed, all channels are simultaneously performed, and at that time, those at adjacent positions are selected. This is because there is a strong correlation between data at adjacent locations, so that it is possible to perform more accurate gain adjustment and offset adjustment if sampling is performed while ensuring that correlation.

In a general photographing situation, the main subject is often present in the central portion of the photographing screen, so that the central portion of the photographing screen may be sampled with emphasis. On the other hand, when the subject is not limited to the central portion as in landscape photography, the entire photography screen may be dispersedly sampled. Also, by providing a switch etc.,
The sampling range may be selected depending on the shooting situation. The pixel signal sampled in this way is stored in the buffer memory 9. Next, the CPU 10
Calculates the offset error and the gain error using the sampling data stored in the buffer memory 9 by the following method.

In the following explanation of the operation of the CPU 10, the output is n channels, and m channels are adjacent to each other.
A case where one pixel is sampled and used will be described. Let Xik be the input light quantity input to the pixel at the kth sample point of the i-th channel of the CCD, Yik be the output signal output from the pixel at the kth sample point of the i-th channel, and take the photoelectric conversion characteristics into consideration. The gain of the i-th channel is Gi, and the offset voltage of the i-th channel is D
If i, the output signal Yik is expressed by the following equation.

## EQU1 ## Yik = Gi.Xik + Di (1) Here, when the reference signal output is the first channel, the output signal Y1k is expressed by the following equation.

[Formula 2] Y1k = G1 · X1k + D1 (2)

Generally, in a photographed image, data are strongly correlated with each other in the vicinity of each pixel.

It can be assumed that Xik = X1k (3), and in this case, the difference between Yik and Y1k is expressed by the following equation.

## EQU00004 ## (Yik-Y1k) = (Gi-G1) .X1k + (Di-D1) (4) From equations (2) and (4),

(5) (Yik−Y1k) = {(Gi / G1) −1} · Y1k + Di− (Gi / G1) · D1 (5) In the equation (5), k is changed from 1 to m, Y1k and Yik-Y1k are obtained for each k,
If the coefficient is obtained by the least squares method, (Gi / G1) -1 and D
i- (Gi / G1) .D1 is obtained. If the value of D1 is known in advance, Gi / G1 (gain error) and Di
(Offset) is calculated.

If the number of channels is large, the assumption of equation (3) may not hold, so that (4),
When taking the difference in the equation (5), it is possible to calculate the error more accurately by taking the difference between the channels as close as possible. For example, when the number of channels is n, the error can be minimized if the reference channel is the n / 2-th channel located in the center of the channel row. Also CCD
It is not necessary to take the difference for all the pixels of 1 according to the equations (4) and (5). If sampling points are selected so that the luminance distribution is uniform, even if only a part of the shooting screen is sampled, it is accurate. The error can be calculated.

In the first embodiment shown in FIG. 1, a, b, c
Of the three channels, the b channel is used as the reference signal and CP
The U10 compares the sampling data of the a and c channels with the sampling data of the b channel, respectively, to calculate the gain error and the offset error according to the equations (4) and (5), and outputs the results to the D / A unit 11 Send to. The D / A unit 11 uses the offset error and the gain error from the CPU 10 to adjust the control voltages Oa, Oc, Va, and Vc so that the offset error and the gain error of the a and c channels become 0, respectively. The signals are sent to the circuits 4a and 4c and the amplifiers 5a and 5c. With the above processing, it is possible to perform offset adjustment and gain adjustment while continuing shooting.

FIG. 2 is a flow chart showing the operation of the CPU 10. This flowchart starts the operation after the CCD 1 captures a subject image. In step S1, the sampling circuit 8 is instructed to start sampling of pixel signals. In step S2, the sampling circuit 8
The data stored in the buffer memory 9 is controlled to be stored in the buffer memory 9 (hereinafter sometimes simply referred to as data). In step S3, it is determined whether or not the required number of samplings have been completed.
Return to 2. On the other hand, if it is determined that the processing is completed, step S
Go to 4. In step S4, a histogram of b channel data (distribution of pixel output values at each pixel position) is created, and the process proceeds to step S5. Step S5
Then, it is determined whether or not the created histogram is valid.
If the pixel output values of the histogram, that is, the brightness distribution of the captured image, is concentrated only around a specific brightness such as one black color or one white color, even if the error between channels is calculated with that data, the reliability of Since high adjustment cannot be performed, the data in that case is determined to be invalid. On the other hand, if the luminance distribution is uniform, that is, if there are data of various luminances on average, it is determined as valid data, and the process proceeds to step S6.

In step S6, i and k are changed to Y.
ik-Y1k is obtained, the horizontal axis is Y1k, and the vertical axis is Yik-Y.
When the data is plotted as 1k, the slope and intercept of a straight line (hereinafter, referred to as a prediction error straight line) that passes through the approximate center of the plotted portion are obtained. In step S7,
The difference between the point on the prediction error line and each plot location is calculated. In step S8, the variance of each difference calculated in step S7 is calculated, and the process proceeds to step S9. In step S9, it is determined whether the variance exceeds a predetermined value. If it is determined that the predetermined value is not exceeded, step S
Then, the process shifts to 10, and it is determined whether or not each difference calculated in step S7 exceeds a predetermined value. If each difference exceeds a predetermined value, the process proceeds to step S11, the gain error and the offset error are calculated from the prediction error straight line obtained in step S6, the values are sent to the D / A unit 11, and the process is ended. . When it is determined in step S10 that each difference does not exceed the predetermined value, the process ends. When it is determined in step S9 that the variance exceeds the predetermined value, the process proceeds to step S12, and error processing, for example, a warning that proper error adjustment cannot be performed is performed and the processing ends. If it is determined in step S5 that the data is not valid from the result of the histogram, the process proceeds to step S13, the sampling point is changed, and the process proceeds to step S14. In step S14, it is determined whether or not the sampling points have been changed a specified number of times, and if the specified number of times has not been reached yet, the process returns to step S1 and the histogram of the data is created again. on the other hand,
When the specified number of times is reached, the process is terminated through step S12.

In the process of FIG. 2, the CPU 10 determines whether or not the sampling data is suitable for performing the offset adjustment and the gain adjustment, and only when it is determined that the sampling data is suitable, the sampling data is used for adjustment. Therefore, the adjustment accuracy can be improved. Then, when the sampling data is not suitable for the adjustment, the photographer is warned to that effect, so that the adjustment can be redone easily. In addition, since the adjustment is performed after considering the magnitude of the difference between the prediction error line and each data and the variance value of the difference, highly reliable adjustment is possible. Further, when the difference is small or the variance value is large, the photographer is warned that the adjustment will not be performed, so that unnecessary adjustment can be avoided, the adjustment can be redone easily, and the adjustment time can be shortened. In addition, CPU
10 may be configured to automatically perform the processing of FIG. 2 at regular time intervals during shooting by providing a timer or the like,
Alternatively, it may be performed at the instruction of the photographer. If you want to automatically perform every fixed time, install a timer, operate the timer at the time of performing the offset adjustment and the gain adjustment, and after the time measured by the timer has passed the fixed time, reset the timer, Figure 2
The above process may be repeated. Alternatively, the adjustment may be performed at regular time intervals while the main switch of the camera is on. As a result, it is possible to always perform shooting with the optimum adjustment value.

As described above, in the first embodiment, a, b, c
When a CCD having three-channel output is used for photographing, offset error and gain error of other channels are obtained with reference to b channel, and offset adjustment and gain adjustment are performed according to the magnitude of the error. Even if the offset or gain of each channel changes due to changes over time, b
It can be automatically adjusted to match the channel. Further, since the gain and the offset are adjusted during shooting, it is not necessary to take special labor for the adjustment, and it is possible to always shoot with the optimum offset and gain.

In the above embodiment, the error from the other channels is detected with the b channel as the reference, but the reference signal output may be the a or c channel other than the b channel.

Second Embodiment In the first embodiment, the offset adjustment and the gain adjustment are performed with the analog signal as it is. On the other hand, in the second embodiment described below, the offset adjustment and the gain adjustment are performed after converting the digital signal. Figure 3
2 is a block diagram of the second embodiment, and the portions common to the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Reference numerals 21a, 21b, and 21c are A / D converters, which output the noise reduction & sampling circuits 3a, 3b, and 3c for each channel according to a clock synchronized with the transfer rate of pixel information input from the CCD drive circuit 2. To each digital signal. Two
Reference numerals 2a, 22b and 22c are offset adjustment circuits for adjusting the digital data corresponding to the reference DC voltage of each channel to be equal. The reference voltage level of the offset adjusting circuit 22b is adjusted by a preset control digital signal, and the offset adjusting circuit 22a,
The reference voltage level of 22c is adjusted by the adjustment control circuit 25 described later.
It is adjusted by the control digital signals ODa and ODc input from. Reference numerals 23a, 23b and 23c are amplifiers for amplifying digital data of each channel,
Is a fixed amplifier that amplifies the b-channel digital data with a preset gain, and includes amplifiers 23a and 23c.
Is a variable amplifier whose amplification degree changes according to the control digital signals VDa and VDc input from the adjustment control circuit 25. Thereby, the digital data corresponding to the maximum and minimum signal amplitude of each channel is adjusted to be equal. A sampling circuit 24 includes amplifiers 23a and 2a.
Digital data of each channel from 3b and 23c is sampled and the sampled data is stored in the buffer memory 9. Reference numeral 25 denotes an adjustment control circuit, which is the CPU 10
Using the gain error and the offset error calculated by, the control digital signals ODa, ODb, VDa, VDc are sent to the offset adjustment circuits 22a, 22c and the amplifiers 23a, 23c so that the respective errors become zero.

The operation of the second embodiment will be described with reference to FIG. 3. The pixel information picked up by the CCD 1 is subjected to noise removal and sampling by the noise reduction & sample hold circuits 3a, 3b, 3c, and then, The signals are converted into digital signals by the A / D converters 21a, 21b, 21c.
The pixel information converted into the digital signal is subjected to offset adjustment by the offset adjustment circuits 22a, 22b, 22c, and then gain adjusted by the amplifiers 23a, 23b, 23c. The signals whose gains have been adjusted by the amplifiers 23a, 23b, and 23c are sent to the multiplex circuit 6 and the sampling circuit 24. Sampling circuit 24
Then, a part of the pixel signal of each channel is sampled and the result is stored in the buffer memory 9. The CPU 10 uses the digital signal stored in the buffer memory 9,
Similar to the first embodiment, the gain error and the offset error are calculated. The calculated gain error and offset error are sent to the adjustment control circuit 25. In the adjustment control circuit 25, CP
Using the gain error and offset error from U10,
The control digital signals ODa, ODc, V are set so that both the offset error and the gain error of the a and c channels become 0.
Da and VDc are offset adjustment circuits 22a and 22d, respectively.
22c and amplifiers 23a and 23c.

As described above, in the second embodiment, since the offset adjustment and the gain adjustment are performed after the conversion into the digital signal, the influence of noise etc. is less likely to occur during the adjustment. In addition, control digital signals ODa, ODc, VDa,
Since the offset adjustment and the gain adjustment are digitally performed by VDc, the error in the adjustment is reduced.

In the second embodiment, the sampling circuit 24 samples by using the outputs of the amplifier circuits 23a, 23b, 23c, but the output of the multiplex circuit 6 is the same as in the first embodiment. It is also possible to perform sampling and distribute the data for each channel based on the sampling result.

-Third Embodiment-In each of the first and second embodiments, a CPU is provided inside the image pickup apparatus, and the offset error and the gain error are calculated by this CPU. Although it has an advantage that the gain can be adjusted, generally, once the offset adjustment and the gain adjustment are performed, an error does not occur in the offset and the gain even if they are not frequently performed thereafter. Therefore, in the third embodiment, the sampling circuit, the buffer memory, and the CPU are provided outside the image pickup apparatus.

FIG. 4 is a block diagram of the third embodiment.
The same parts as those of the first and second embodiments are designated by the same reference numerals, and the description thereof will be omitted. Reference numeral 31 denotes an interface circuit, which includes an adjuster 32 and an image pickup apparatus 100 provided outside.
Information transmission with. The adjuster 32 includes a sampling circuit 321, a buffer memory 322, and a CPU 3.
23. That is, in the third embodiment, the interface circuit 31 is provided without the sampling circuit, the buffer memory, and the CPU inside the image pickup apparatus 100.
By connecting the adjuster 32 via the, the offset adjustment and the gain adjustment are performed as in the first and second embodiments.

The operation of the third embodiment will be described with reference to FIG. 4. When the image pickup apparatus 100 is initially set, the image pickup apparatus 1
After connecting the adjuster 32 to 00, start shooting and set the CCD
A subject image is picked up by 1. The picked-up pixel signal is used for the noise reduction & sample hold circuit 3a,
3b, 3c, offset adjustment circuits 4a, 4b, 4c, amplifier circuits 5a, 5b, 5c, multiplex circuit 6, and A / D converter 7 to be converted into digital signals. A
The digital signal from the / D converter 7 is sent to the adjuster 32 via the interface circuit 31. In the adjuster 32, according to the instruction of the CPU 323, the sampling circuit 3
At 21, a part of the captured image is sampled and stored in the buffer memory 322, and the stored sampling data is used to calculate the offset error and the gain error as in the first and second embodiments. The calculated offset error and gain error are transferred to the EEPRO via the interface circuit 31.
It is stored in M14. After the above processing, the adjuster 32 is removed from the imaging device 100.

In a normal use state of the image pickup apparatus 100, when the power source (not shown) of the image pickup apparatus 100 is turned on, the EEPR
The offset error and the gain error stored in the OM 14 are automatically sent to the D / A unit 11 and converted into control voltages Oa, Ov, Va, Vc by the D / A unit 11, and then each offset adjustment circuit 4a. , 4c and amplifier circuit 5a,
5c, and offset adjustment and gain adjustment are performed.

As described above, in the third embodiment, the regulator 3
2 is provided outside the imaging device 100, the imaging device 10
The configuration of 0 can be simplified and the cost can be reduced. Further, the adjuster 32 can be easily attached to and detached from the image pickup apparatus 100, and with the adjuster 32 attached, the adjustment can be performed in the same manner as in the first and second embodiments, so that there is no adjustment inconvenience. Therefore, when performing only the initial adjustment of the imaging device 100,
A third embodiment can be used.

In the third embodiment, the offset adjustment or the like is performed with the analog data as it is as in the first embodiment. However, like the second embodiment, the offset is adjusted after being converted into digital data. Adjustment or the like may be performed. In the first to third embodiments, the gain adjustment is performed after the offset adjustment, but the offset adjustment may be performed after the gain adjustment. Further, in the above-mentioned first to third embodiments, the case where the CCD having the three-channel output is used as the image pickup element has been described, but the image pickup element is not limited to the CCD, and may be a MOS type image pickup element or a mixed type of CCD and MOS. Various image pickup devices such as the above image pickup device may be used. In addition, the number of output channels is 2
The number of channels is not limited to 3 and the number of channels is not limited. However, if there are many channels, as described above,
Since the distance to the reference channel is large, the error becomes large. Therefore, in such a case, the reference channel may be sequentially changed to detect the error.

In the embodiment thus constructed, C
The CD 1 serves as an image pickup means, and the offset adjustment circuits 4a, 4b,
4c is a DC voltage adjusting means, amplifiers 5a, 5b and 5c are amplifying means, a sampling circuit 8 is an extracting means, and a CPU
Reference numeral 10 corresponds to the calculation means, the first evaluation means, and the second evaluation means, respectively.

[0034]

As described above in detail, according to the present invention, each channel output from the image pickup means such as CCD is extracted, and the extracted data are compared with each other to adjust the DC voltage level of each channel. Since the amount and the gain adjustment amount are calculated, the adjustment accuracy is improved and the adjustment can be automated. Also, because you can make adjustments while continuing shooting, you do not have to take special steps for adjustment, and adjustments are made immediately even if shooting conditions such as temperature changes change.
You can always shoot in the optimal state. Particularly, in the invention described in claim 2, since the DC voltage level adjustment and the gain adjustment are performed according to the difference between the extracted data of the predetermined channel and the extracted data of the other channel, the adjustment process is simplified. In the invention according to claim 3, the first evaluation means is provided to determine whether or not the extracted data is suitable for obtaining the difference. Only when it is determined that the extracted data is suitable, the difference is calculated by the calculation means. Therefore, the adjustment accuracy can be improved. Further, a second evaluation means is provided to determine whether or not the obtained difference is suitable for calculating the DC voltage level adjustment amount and the gain adjustment amount. Only when it is determined to be suitable, the difference is determined. Since I tried to calculate
The adjustment can be performed with high reliability, and unnecessary adjustment can be avoided.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of an image pickup apparatus according to the present invention.

FIG. 2 is a flowchart showing an operation of the CPU of FIG.

FIG. 3 is a block diagram of a second embodiment of the image pickup apparatus according to the present invention.

FIG. 4 is a block diagram of a third embodiment of the image pickup apparatus according to the present invention.

[Explanation of symbols]

1 CCD 2 CCD drive circuit 3a, 3b, 3c Noise reduction & sample hold circuit 4a, 4b, 4c Offset adjustment circuit 5a, 5b, 5c Amplifier 6 Multiplex circuit 7 A / D converter 8 Sampling circuit 9 Buffer memory 10 CPU 11 D / A unit 12 signal processing circuit 13 D / A converter 14 EEPROM

Claims (4)

[Claims] 1. An image pickup means having a plurality of channel outputs,
In an imaging device having a DC voltage adjusting means for adjusting the DC voltage level of each channel output from the imaging means and an amplifying means for applying a gain to each channel output from the imaging means, each channel output from the imaging means is Extraction means for extracting, and by providing a calculation means for calculating the DC voltage level adjustment amount and the gain adjustment amount by comparing the extraction data for each channel extracted by the extraction means, the DC voltage adjustment means is An image pickup apparatus, characterized in that a DC voltage level is adjusted based on a result of a calculating means, and the amplifying means adjusts a gain based on a result of the calculating means. 2. The image pickup device according to claim 1, wherein the arithmetic unit obtains a difference between the extracted data of a predetermined channel and the extracted data of another channel, and the DC voltage level adjustment amount is calculated according to the difference. And an image pickup apparatus, wherein the gain adjustment amount is calculated. 3. The image pickup apparatus according to claim 2, further comprising: first evaluation means for determining whether or not the extracted data extracted by the extraction means is suitable for obtaining the difference by the calculation means. A second determination is made as to whether or not the difference obtained by being determined to be suitable by the first evaluation means is suitable for calculating the DC voltage level adjustment amount and the gain adjustment amount.
The image pickup device, wherein the calculation means calculates the DC voltage level adjustment amount and the gain adjustment amount when the second evaluation means determines that the DC voltage level adjustment amount is suitable. 4. The image pickup device according to claim 1, further comprising a time measuring unit that measures time, and a DC voltage is provided every time a time measured by the time measuring unit exceeds a predetermined time. An image pickup apparatus characterized by performing level adjustment and gain adjustment.